Roger Federer was in tears as he won a thrilling, five-set Australian Open final against his great rival Rafael Nadal to clinch a record-extending 18th Grand Slam title on Sunday.

Federer won a classic, fluctuating encounter 6-4, 3-6, 6-1, 3-6, 6-3 in three hours 38 minutes to move four major titles ahead of Nadal and Pete Sampras on the all-time winners' list.

"Tennis is a tough sport, there's no draws. But if there was going to be one I would have been very happy to accept a draw tonight and share it with Rafa, really," Federer said, as he accepted the trophy from Australian legend Rod Laver.

"Keep playing please, Rafa. Tennis needs you."

After an astonishing comeback from six months out with injury, the Swiss became the oldest man in the post-1968 Open era to win a major since Ken Rosewall at the 1972 Australian Open.

It was Federer's fifth Australian title in his sixth final, and ended a long, seven-year wait to win again in Melbourne after his 2010 triumph over Andy Murray.

It was the 35th meeting between the two long-time rivals with Nadal now leading 23-12 and 6-3 in major finals, including his five-set win over Federer in the 2009 Australian final.

And it was a final to suit the occasion as momentum shifted from one side to the next before Federer finally seized control in the deciding set.

- Jumping for joy -                 

"It's amazing how well he's playing after being away for so long. For sure, you have been working a lot to make that happen. I am very happy for you," Nadal told the crowd.

"It was a good month for me, amazing month for me, really enjoyed it. I worked very hard to be where I am today. Probably Roger deserved it a little bit more than me."

"I'm just going to keep on trying. Feel like I'm back to a very high level. I'll keep fighting this season."

Federer, playing aggressively and with a flatter backhand than normal, took the match to Nadal and got the only service break to take the opening set.

Nadal fought back with two breaks to level before Federer got the bit between his teeth with a double break in the third set.

The Spaniard hit back in the fourth set with a service break in the fourth game to take the final into a fifth set.

He again broke the Swiss early in the final set but Federer stirred himself and broke Nadal twice to win an epic encounter as he served out for a brilliant victory, jumping for joy as he did so and crying tears of joy.

A final between Federer and Nadal had been wholly unexpected but the veterans seized their chance after top seeds Andy Murray and Novak Djokovic made early exits.

Federer becomes the first man in history to win five or more titles at three different Grand Slam events. He has won five Australian Opens, seven Wimbledons, five US Opens and one French Open.